Added call to ParquetWriter.close in Bam2Adam.
Adding the ListDict command.

Includes
(1) a new Projection-like class, for the fields from the ADAMSequenceRecord schema.
(2) A new enumeration, ADAMSequenceRecordField, to be used within that class.
(3) ListDict command itself, which simply prints the order, name, and length of the sequences in teh sequence dictionary.